Ductal hamartoma of the pancreas: A clinicopathologic study

Benign ductular proliferative lesions that resemble hepatic von-Meyenburg Complexes(VMC)/bile duct hamartomas have been noted to occur in the pancreas, but their incidence, clinicopathologic features and pathogenesis remains unknown. We present herein 3 patients that presented as cysts and call them pancreatic ductal hamartomas (PDH).

Three cases of PDH were identified form a multi-institutional collaborative group, and their clinicopathological were reviewed. In addition, we also examined 115 consecutive pancreatic resections at our institutions for the presence of incidental PDHs.

The lesions were detected in each case during imaging for abdominal symptoms or grossing. The clinical suspicion was intra-ductal pancreatic mucinous cystic neoplasm (IPMN) in each case that led to pancreatectomy. The cyst fluid CEA was elevated in 2 of the patients tested. The patient age and gender were 73/M (case1), 68/F (case2) and 73/M (case3). In case1 besides the larger cystic lesion, numerous tiny lesions (0.1-0.3 cm) were seen throughout the pancreas. In case2 this was the only lesion, while in case3 there was another gastric-type IPMN with high-grade dysplasia. PDH were identified in 5(4.3%) of 115 consecutive pancreatectomy specimens. The PDHs measured 0.1-2.3 cm, and the histology is characterized by proliferation of irregular ductal structures lined by bland flattened to low columnar epithelium, variable cystic change and inspissated luminal secretions. The lining epithelium varied from non-mucinous pancreatico-biliary type to mucinous gastric foveolar-type, with occasional squamous metaplasia.

PDH are seen in 4.5% of all pancreatectomy specimens and detected incidentally, but occasionally may become large and/or cystic enough leading to pancreatectomy. Their relationship to pancreatic carcinoma or IPMN remains currently unknown.